1. Field of the Invention
Aspects of the present invention relate to a thin film transistor, a method of fabricating the same, and an organic light emitting diode display device including the same.
2. Description of the Related Art
In general, a polycrystalline silicon layer is widely used as a semiconductor layer is of a thin film transistor, because of its high field effect mobility and its applicability to a high-speed circuit and/or a complementary metal-oxide semiconductor (CMOS) circuit. A thin film transistor using such a polycrystalline silicon layer is used as a switching device of an active matrix liquid crystal display (AMLCD) device. Such a thin film transistor is also used as a switching device and/or a driving device of an active matrix organic light emitting diode display device (AMOLED).
The polycrystalline silicon thin film transistor used in the active matrix display devices is generally a floating body polycrystalline silicon thin film transistor (poly-Si TFT) having a floating, island-shaped semiconductor layer. As a floating body polycrystalline silicon thin film transistor is scaled down, it leads to a reduced drain current and a reduced saturation region thereof.
To solve this problem, a gate-body contact TFT, in which a semiconductor layer is connected with a gate electrode, has been proposed. The gate-body contact TFT has an enhanced sub-threshold slope value and a high drain current at a low gate voltage. Accordingly, an on/off characteristic can be achieved, even at such a low gate voltage, resulting in a low-power, flat panel display device.
Conventionally, a body contact region that contacts a gate electrode was separately formed, so as to extend from a conventional semiconductor layer having no body contact region, in order to implement a gate-body contact thin film transistor. However, this configuration increases an area occupied by a semiconductor layer and the body contact region, and is inappropriate for device integration.